Thiophosphate salts of aralkylene diamines as antiwear,extreme pressure and oxidation inhibitor agents



United States Patent 3,519,563 THIOPHOSPHATE SALTS OF ARALKYLENE DI- AMINES AS ANTIWEAR, EXTREME PRESSURE AND OXIDATION INHIBITOR AGENTS Warren Lowe, El Cerrito, Califi, assignor to Chevron Research Company, San Francisco, Calif., a corporation of Delaware No Drawing. Filed Oct. 31, 1967, Ser. No. 679,570 Int. Cl. C10m 1/48 U.S. Cl. 252-32.7 3 Claims ABSTRACT OF THE DISCLOSURE Oil soluble phosphorodithioic acid salts of aralkylene diamines are provided as antiwear agents, extreme pressure agents and oxidation inhibitors in lubricating oils.

BACKGROUND OF THE INVENTION Field of the invention In order to reduce friction and increase the load-carrying capacity of lubricants employed under boundary or extreme pressure condititons, additives are employed which have come to be known as EP (extreme pressure) agents. At high loads, these additives prevent the welding of asperities of two contacting surfaces which might otherwise occur, followed by metal transfer (galling) or cleavage in production of wear fragments. A commonly used additive is zinc dithiophosphate. However, as efforts have been made to reduce the amount of metal present in modern-day lubricating oils, which frequently result in metal deposits, alternatives to zinc dithiophosphate have been sought.

Description of the prior art Various ashless extreme pressure agents have been reported. See for example U.S. Pat. No. 3,317,426. Also, dithiophosphates salts of amines have been disclosed in U.S. Pat. No. 3,002,014.

SUMMARY OF THE INVENTION Ashless (metal free) extreme pressure agents and oxidation inhibitors are provided which are monoor disalts of oil soluble dithiophosphoric acids and chlorinated aralkylene diamines, wherein the amino groups are bonded to a saturated aliphatic carbon atom. These additives are particularly useful in lubricating oils for internal combustion engines, reducing the amount of metal in the oil which may form deposits.

DESCRIPTION OF PREFERRED EMBODIMENTS Compositions The compositions of this invention have the following formula:

wherein R is a hydrocarbon radical of at least eight carbon atoms, usually of not more than 30 carbon atoms, and more usually in the range of about 10 to 18 carbon atoms; U is alkylene of from 1 to 4 carbon atoms, more usually of from 1 to 2 carbon atoms; Ar is an aromatic hydrocarbon group of from 6 to 12 carbon atoms; X is halogen of atomic No. 17 to 35 (chlorine and bromine); l is a number in the range of l to 2, m is an integer of from 2 to 4, n is a number in the range of 0 to 1, and the sum of l and n is 2.

Patented July 7, 1970 ice wherein R and R are hydrocarbyl of from 8 to 30 carbon atoms, more usually of from 10 to 18 carbon atoms, and preferably alkaryl; X is halogen of atomic No. 17 to 35, preferably chlorine; m and m are in the range of 2 to 4, preferably 4 and the disposition of the methylene amino groups is meta or para, particularly para.

Considering the radicals individually, R (including R and R may be aliphatic hydrocarbon or alkaryl hydrocarbon to provide a phosphorodithioic acid which is oil soluble. Illustrative hydrocarbon groups are octadecyl, tetradecyl, dodecyl, tetrapropenylphenyl, pentapropenylphenyl, tetradecylphenyl, etc. The preferred R groups are alkaryl, particularly alkylphenyl. Illustrative phosphorodithioic acids which find use are 0,0-di(tetrapropenylphenyl) phosphorodithioic acid, 0,0-dioctadecyl phosphorodithioic acid, 0,0 di(dioctylphenyl) phosphorodithioic acid, 0,0 di(tetrapropenylphenyl) phosphorodithioic acid, 0,0 di(dodecylphenyl) phosphorodithioic acid, etc.

The amines which find use to form the salts will generally be from 8 to 14 carbon atoms and have from 2 to 4 halogen atoms, chlorine or bromine. The aromatic ring will generally have from 1 to 2 rings, either fused or non-fused, e.g., diphenyl and naphthalene. The alkylene groups bonding the amino group to the aromatic ring may be straight or branched, though usually polymethylene. Preferably, the aminoalkylene substituents on the aromatic rings will be separated by at least 3 annular carbon atoms and more preferably 4 annular carbon atoms, i.e., meta and para on the benzene ring.

Illustrative amines include dichloro-p-xylylene diamine, trichloro-p-xylylene diamine, tetracholro-p-xylylene diamine, tetrabromo-p-xylylene diamine, tribromo-pxylylene diamine, dichloro di(Z-aminoethyl) benzene, tetrachloro di(Z-aminoethyl) benzene, tetrachloro 1,8-di (aminomethyl) naphthalene, etc.

The composititons are readily prepared by combining the phosphorodithioic acid with the desired amine in the stoichiometric proportions to provide the monoor disalt or mixture thereof, either neat or in the presence of a suitable solvent. The temperature for the reaction will generally be in the range of about F. to 300 F., more usually in the range of about F. to 225 F. The product may be isolated directly or purified as required.

Oil compositions The compositions of this invention will be employed in lubricating oils in from about 1-10 weight percent, more usually from 2-5 weight percent. When used as concentrates to be subsequently diluted, there will be from about 1050 weight percent of the subject compositions in the oil composition.

The lubricating oils used with the compounds of this invention may be derived from natural or synthetic sources. Fluids of lubricating viscosity generally have viscosities of from about 35 to 50,000 Saybolt Universal Seconds (SUS) at 100 F. Among natural hydrocarbonaceous oils are paraflin base, naphthenic base, asphaltic base and mixed base oils. Illustrative of synthetic oils are hydrocarbon oils, such as polymers of various olefins, generally of from 2 to 6 carbon atoms, and alkylated aromatic hydrocarbons; and non-hydrocarbon oils, such as polyalkylene oxides, aromatic ethers, and silicones. The preferred media are the hydrocarbonaceous media, both natural and synthetic.

Besides the additives of this invention, other additives will be normally present in the lubricating oils. These additives include detergents, rust inhibitors, antioxidants, oiliness agents, foam inhibitors, viscosity index improvers, pour point depressants, etc. Usually, these other additives will be present in the range from about 0.1 to 15 weight percent, more usually from about 0.5 to weight percent of the total oil composition. Generally, an individual additive will be present in from about 0.01 to 5 Weight percent of the total composition. It is of particular importance that the compositions of this invention are compatible with the various additives and do not interfere with their effectiveness.

The compositions of this invention find particular use with ashless lubricating oil detergents which are alkenyl succinimides of alkylene polyamines, having molecular weight in the range of 1,000 to 5,000, such as the monoand di(polyisobutenyl) succinimide of alkylene polyamines, partiularly ethylene polyamines of from 3 to 6 amino groups, wherein the polyisobutenyl group is of about 700 to 1,500 molecular weight. See U.S. Pat. Nos. 3,219,666, 3,272,746 and 3,172,892.

Preparation and testing The following examples are offered by way of illustration and not by way of limitation.

EXAMPLE 1 Into a reaction flask was introduced 27.2 g. of tetrachloro-p-xylylene diamine and 103 g. of 0,0-di(tetrapropenylphenyl) phosphorodithioic acid and the mixture heated at 170 F. with stirring. After a short while, the reaction flask was transferred to a steam plate and stirred slowly for a time sufficient to complete reaction. The product was then cooled and isolated.

EXAMPLE 2 Into a reaction fiask was introduced 54.5 g. of tetrachloro-p-xylylene diamine and 412 g. of 0,0-di(tetrapropenylphenyl) phosphorodithioic acid and the mixture heated and stirred at ZOO-210 F. for about 8 hours. The mixture was then allowed to cool and the product isolated.

In order to demonstrate the eifectiveness of the compounds of this invention as extreme pressure agents, the compounds of Examples 1 and 2 were tested under the Falex EP Wear and Shear Test. The test is described in Journal of the Institute of Petroleum 32, Apr. 19, 1946. The figures reported are the loads under which the particular lubricating oil composition failed, that is, seizure occurred. Also reported is the wear on the rod when applying a load of 850 pounds for a period of 30 minutes. The value reported is the lost Weight in milligrams resulting from wear on the rod.

The oil used was 480 neutral oil having 5 weight percent of polyisobutenyl succinimide of tetraethylene pentamine (polyisobutenyl of approximately 1,000 molecular weight) and 0.1 weight percent of terephthalic acid (a corrosion inhibitor). To this oil was added 18 mm./kg. based on phosphorous of the exemplary compounds of Examples 1 and 2. The results reported are for the oils with and without the additives of this invention.

An oxidation test was carried out to determinethe effectiveness of the compounds of this invention as oxidation inhibitors. Two oil samples were prepared using 480 neutral oil containing 5 weight percent of a commercial ashless detergent (same as used above) and 0.1 weight percent of terephthalic acid (corrosion inhibitor). Into one of the samples was added the exemplary composition of Example II in an amount providing a concentration of 18 mm./kg. of phosphorous. To 25 g. aliquots of each of the above samples were added 0.2 cc. ofa solution having 3,160 p.p.m. of copper, 2,670 p.p.m. of iron, p.p.m. of manganese, 36,700 p.p.m. of lead and 1,631 p.p.m. of tin as their naphthenates, providing a distribution of metals which would be expected to be found in used crankcase oils after an L4 Chevrolet Engine Test. The oil sample to be tested is then maintained at 340 F. and the time required to absorb 1,000 ml. 0 observed. Without the additive, the oxygen was absorbed in 0.7 hours, while the sample with the additive required 7.8 hours.

The above results demonstrate the excellent protection from wear and the great enhancement in lubrication resulting by the addition of the compounds of this invention to a compounded oil. Also, significant oxidation inhibition is also observed. It is evident that the compounds of this invention afford excellent protection under extreme lubricating conditions. Moreover, the compounds of this invention are compatible with a wide variety of additives which are included in compounded oils as demonstrated by their activity with a common commercial ashless detergent, e.g., alkenyl succinimides, and a common corrosion inhibitor, e.g., terephthalic acid.

What is claimed is:

1. A lubricating oil composition having a major amount of an oil of lubricating viscosity and, in an amount suflicient to provide extreme pressure properties to said lubricating oil, a compound of the formula:

wherein R is a hydrocarbon from 8 to 30 carbon atoms, Ar is an aromatic hydrocarbon group of from 6 to 12 carbon atoms, U is alkylene of from 1 to 4 carbon atoms, X is halogen of atomic No. 17 to 35, l is a number in the range of 1 to 2, m is an integer of from 2 to 4, n is a number in the range of 0 to 1 and the sum of l and n is 2.

2. A composition according to claim 1 wherein U is methylene, Ar is phenylene and X is chlorine.

3. A composition according to claim 1 wherein U is methylene, Ar is phenylene, X is chlorine, and m is 4.

References Cited UNITED STATES PATENTS 2,285,855 6/1942 Downing et a1. 2,798,045 7/1957 Buck et a1. 2,973,323 2/1961 Millikan et a1. 3,103,492 9/ 1963 Dinsmore et al. 3,112,267 11/1963 Price et a1. 3,340,329 9/ 1967 Guarnaccio et a1 252403 FOREIGN PATENTS 525,353 5/1956 Canada.

DANIEL 'E. WYMAN, Primary Examiner W. J. SHINE, Assistant Examiner U.S. Cl. X.R. 252403 

